1. Technical Field
This invention relates to the cleaning of surfaces, and, more particularly, to an improved method of reducing foreign particulate matter on surfaces of semiconductor wafers.
2. Description of the Prior Art
In the manufacture of semiconductor devices, cleaning steps are performed before or after various steps to remove foreign contaminants or impurities from the surfaces of semiconductor wafers. For example, wafers are commonly polished with abrasive slurries to produce smooth, polished surfaces; after polishing, it is necessary to remove the slurry and other surface contaminants from the wafers. Removal of foreign particulate matter, such as metallics and organic contaminants, is also required prior to high temperature processing steps, such as diffusion, thermal oxidation and epitaxial growth; otherwise, these impurities can adversely affect surface stability, reliability, electrical performance and production yield of devices. Cleaning steps are also commonly carried out after stripping photoresist materials from the surfaces of wafers and following etching steps.
Various techniques are used to clean foreign particulate matter from the surfaces of semiconductor wafers, such as chemical removal, centrifugation, air-stream or water jet cleaning, mechanical scrubbing and so forth. One commonly used chemical cleaning solution contains sulfuric acid and hydrogen peroxide (see, for example, Kern, W., "Hydrogen Peroxide Solutions For Silicon Wafer Cleaning", RCA Engineer 28-4 (July/August, 1983), pp. 99-105), but that solution is somewhat limited in its foreign particulate matter removal effectiveness. Other methods employing various cleaning solutions are exemplified by the disclosures in the following: U.S. Pat. No. 4,261,791, issued to Schwartzman on Apr. 14, 1981; U.S. Pat. No. 4,711,256, issued to Kaiser on Dec. 8, 1987; and U.S. Pat. No. 4,828,751, issued to Kremer on May 9, 1989.